A common fluid coupling construction is to employ complementary male and female components which, when fully interconnected, permit the flow of fluid through the coupling. The coupling halves may include self-sealing valve structure which is closed when the coupling halves are separated, and automatically opens during the coupling of the intermating components.
The male probe is normally of a cylindrical construction and an annular seal within the female half recess sealingly engages the male cylindrical surface. During disconnection of the coupling halves a subatmospheric pressure or vacuum will be created within the female part as the probe is withdrawn. This subatmospheric pressure increases the force necessary to disconnect the coupling parts. This effect is quite serious when encountered in relatively large hose coupling sizes such as those used to refuel aircraft, and difficulty in disconnecting the coupling parts of a refueling system creates a serious safety hazard.
It is an object of the invention to provide a fluid coupling seal which effectively seals intermating coupling halves during fluid flow through the coupling but prevents the creation of a vacuum within the coupling during disconnection of the coupling parts.
Another object of the invention is to provide a vacuum breaking seal within a fluid coupling which is of an economical construction to manufacture and is dependable in operation.
Yet another object of the invention is to provide a vacuum breaking seal for intermating coupling parts which may be easily retrofitted to existing couplings without requiring modification thereto.
A further object of the invention is to provide a vacuum breaking seal which may be readily manufactured, easily installed in a fluid coupling, even though retrofitted to an existing design, and prevents the formation of subatmospheric pressure within the female coupling part during withdrawal of the male probe.
In the practice of the invention an annular recess intersects a cylindrical surface of one of the coupling halves, usually the passage of the female member. The other coupling half, such as the cylindrical male probe, is received within the recess, and an annular resilient seal located within the groove sealingly engages the cylindrical surface of the probe. The seal prevents leakage during the flow of pressurized medium through the coupling halves, and a sealed relationship between the female part and the male probe part occurs as soon as the male probe surface is engaged by the seal.
In accord with the invention, the annular seal includes an inner portion engaging the probe cylindrical surface and thereby establishes a seal between the male and female parts. Additionally, the annular seal includes first and second radially extending ends which are in an opposed relationship to the radial sides of the groove in which the seal is received.
An annular lip or flapper seal is homogeneously defined on the seal body having a base connected to an end of the seal and a deformable free end which may sealingly engage a groove side. The lip is obliquely related to the axis of the seal and includes an inner pressure face which is subjected to the pressurized medium within the coupling whereby such pressure forces the lip against the groove end and prevents leakage about the outer circumference of the seal during coupling pressurization.
The end of the seal opposite to that end upon which the lip is defined is exposed to atmospheric pressure, and this seal end includes a plurality of radially extending channels defined by radially ribs. In a like manner the outer circumference of the seal is provided with a plurality of axially extending channels in communication at one end with the seal end channels, and at the other end communicate with the atmospheric side of the lip which is opposed to the lip pressure side.
During coupling connection and operation the internal pressure within the coupling is prevented from escaping due to the sealed relationship between the male probe and the seal inner bore rib, and medium cannot flow about the coupling as pressure acting upon the lip maintains a sealed relationship between the lip free end and the associated groove surface.
When the probe is being withdrawn from the female coupling half such axial probe displacement creates a subatmospheric pressure within the female half recess. Upon such occurrence, atmospheric pressure flows around the seal through the channels defined upon the seal end and circumference exposing the atmospheric side of the seal to atmospheric pressure while the pressure face of the seal is exposed to subatmospheric pressure. The atmospheric pressure deforms the lip permitting atmospheric pressure to flow about the lip to enter the female half recess equalizing the pressures and permiting the parts to be easily separated.
A seal in accord with the invention may be easily retrofitted to existing couplings wherein the female coupling includes a bore having a seal recess by merely removing the old seal and inserting the seal of the invention.